Across the lagoon from Lagos's imposing Le Meridien Eko hotel, the thatched bars of Kuramo Beach offer a less glamorous view of the city's freewheeling nightlife.

Amid the white plastic tables and occasional comatose body on the sand, it is easy to find prostitutes such as Tokwe, a diminutive young woman who says she is 17. Tokwe, who says she typically earns N1,000 ($8, 7, 5) from having sex with four or five men in a night, claims she always uses a condom - but adds that she knows plenty of colleagues who do not.

"Every day they talk on TV that HIV is not good for your body," she says. "[But] some people don't have a TV in their room. They don't have the money to buy a newspaper."

The comment highlights a huge gap in awareness of HIV-related issues that threatens to turn a serious national problem into a disaster. While official HIV infection rates are lower than those of many nations in southern and eastern Africa, Nigeria's huge population means it is one of the worst affected nations in terms of absolute numbers. The country's size, institutional problems and cultural diversity threaten to overwhelm efforts to promote Aids treatment and prevention.

"What me might be seeing is not that the infection rate in Nigeria is lower," says Dr E Oni Idigbe, director-general of the Nigerian Institute of Medical Research. "It may just be that Nigeria is at an earlier phase of the epidemic."

Government statistics show a steady rise in the percentage of people infected with HIV: 1.8 per cent in 1991, 4.5 per cent in 1995 and 5.8 per cent in 2001, although many people think these are underestimates. Given the estimated total population of 128m - or about one-sixth of all the people in sub-Saharan Africa - Nigeria is thought by the health ministry to have the third highest number of infected individuals on the continent, after South Africa and Ethiopia.

Almost as frightening is the way many people seem to be shutting out the problem: in a 1999 government survey, 94.7 per cent of men and 91 per cent of women said they thought their risk of contracting Aids was small or none. "Nigerians seem to be overly confident in their ability to avoid getting Aids," the health ministry notes.

Part of the problem, experts say, is that the issue was not taken sufficiently seriously at an official level during the 15 years of military rule that ended in 1999. It is only in the past few years that posters have appeared showing President Olusegun Obasanjo, the civilian president re-elected this year, putting his arms around infected children.

The government has set up a national body to co-ordinate Aids prevention efforts and oversee a treatment programme intended to offer antiretroviral drugs to 10,000 adult HIV sufferers and 5,000 children.

The initiatives are widely welcomed, although big questions remain over their effectiveness. Professor Babatunde Osotimehin, chairman of the government's National Action Committee on Aids, says the adult antiretroviral programme is well established, although he admits only a small number of people are being helped. Other officials point to problems related to the lack of availability of subsidies for the monitoring tests essential for tracking the drugs' effectiveness.

"There is a funding gap," Prof Osotimehin says. "Nigeria is doing a considerable amount for itself so it looks for its friends [internationally] to assist."

Aids campaigners say the shortage of money is combined with deeper problems relating to Nigeria's vastness, poor infrastructure and culture of corruption. The antiretroviral drugs for the children's programme have not arrived and some drugs for adults never reach hospitals, or are withheld by officials who demand bribes in exchange for treatment.

"The antiretroviral project is not working the way they want it to work," says Mohammed Farouk, executive director of Aids Alliance Nigeria, a Lagos-based non-governmental body. "People are not getting access to drugs."

The difficulties in curbing Aids and preventing HIV infection are amplified by Nigeria's position on one of the main migration and trade routes in west Africa. The World Bank has set up a programme to try to stop the spread of HIV along the road corridor from Abidjan, Ivory Coast's commercial capital, to Lagos, via Ghana, Togo and Benin. The bank says migration in west Africa poses a "unique challenge" that calls for a pan-regional approach as well as for work in individual countries.

Efforts to raise public awareness in Nigeria are hampered by the dominant role played by Christianity and Islam in public life. In a country where thousands of people have died over the past four years in sectarian violence, the influence of religious leaders is strong. The Nigerian Red Cross Society says some churches have forced it to amend its ABC of Aids prevention campaign - abstinence, be faithful and use a condom - to remove the reference to contraception, replacing it with an invocation to good conduct.

"The problem that we have in Nigeria is mainly cultural," says Dr Kunle Aderanti, principal health officer for the Nigerian Red Cross. "It's culturally taboo for children to discuss sex with adults - it's taboo even to discuss sex openly."

As long as drugs remain scarce and discussion of HIV and the reasons for its spread remain restricted, Nigeria is seen as unlikely to achieve the tangible progress in combating HIV achieved by other African nations such as Senegal and Uganda. Even Tokwe, who knows she should take an HIV test, sees the problem of Aids as more susceptible to divine intervention than to any of the practical measures in place. "Money can't solve it," she says. "Only God can solve it."